Alternating-current motor.



No. 841,544. PATENTED JAN.15,.1907. M. G. A. LATOUR.

ALTERNATING CURRENT MOTOR.

APPLICATION FILED AUG.25, 1905.

2 SHEETS-SHEET 1.

Wit/765565: Wye/760W;

PATENTED JAN. 15, 1907.

M. 0. A. LATOUR.

ALTERNATING CURRENT MOTOR. APPLICATION FILED AUG. 25. 1905.

2 SHEETS-SHEET 2.

//71 e/7Z;0/": 7 /0/7215 6. A. A ataur particularly UNITED STATES PATENTOFFICE.

MARI US O. A. LATOUR, OF PARIS, FRANCE, ASSIGNOR TO GENERAL ELECTRIOCOMPANKA CORPORATION OF NEW YORK.

ALTE-RNATtNG-C'URRENT MOTOR.

Specification of Letters Patent.

Patented Jan. 15, 1907.

Application filed August 25,1995. Serial No. 275,745.

To all whom iii-may concern: v

Be it known that I, MARIUS O. A. LATOUR, a-citiz'en of France,'residingat Paris, France, have invented certain new and useful Improvements inAlternating-Current'Motors, of which the following is a specification.

- invention relates to dynamo-electric mac nes of the commutator type,and is applicable to alternating-current motors.

As is well-known in the art, commutation in alternating-current machines'is attended by difliculties which are not present in di- I rect-currentmachines, since 111 the former type an armature-coil whenshort-circuitcd by a brush in commutation is subjected to an alternatingflux which induces short-circult currents in the 0011, which result insparking and excessive heating. This difficulty is most pronounced atstarting when the flux is at a maximum. In order to avoid these shortcircuits in alternating-current machin'esof the commutator type, it hasbeen proposed heretofore to wind the arm ature with a plurality ofindependent windings and to connect these windings to suecessivecommutator-segments. With such an arran ement and with brushes of acertain Widtli no short-circuit currents are produced. For instance, ifthree independent windings are em loyed each segment is .separated fromt e nearest segments connected to the same winding by two other sametime which are connected to the same segments, so that if a brush isused of a Width notgreater than two segments the brush can never-bear ontwo segments at the winding. While this arrangement theoret- 'icallyimproves commutation by avoiding the production of short-circuitcurrents, it has ben found in practice that certain difliculties arise.In every machine thenumber of slots has a certain maximum value abovewhich it cannot be carried Without reducing the size of the teeth tosuch an extent as to increase the reluctance of the magnetic circuitunduly. The number of slots is usually made as great or nearly as greatas is compatible with good design in order to secure the maximumdistribution of the winding, and conse uently the minimum reactance.When a plurality of independent windings are employed, it is clearlynecessary either to sacrifice thisdistr-ibution dr' else to distributeeach winding in every slot. The latter is the preferable course and theone that has been employed heretofore.

theseveral windings in a given slot necesrarily have induced voltages ofthe same phase, since they are in the same osition on the armature-core;but these coi s are connected' to successive commutator-segments, sothat the induced voltages at the commutator-segments do not correspondin phase with the angular positions of the segments. The result as faras commutation is concerned is precisely the same as though'the brushwere shifted back and forth every time a slot passes the brush. It isevident that the best conditions for commutation are not obtained. y I

- My invention consists in distributing each Winding-through all theslots and in so connecting ,the commutator-leads to the several coilsthat theinduced voltage at each lead corresponds in phase to the angularposition of the commutator-segment to which it is connected.

More specifically stated, my invention con sists in connecting adjacentleads to the several coils in a slot at points, on the respective coilsdiffering by a number of turns which bears to the number of turns in acoil a ratio equal to one divided by thenumber of different windings inthat slotthat is, if three windings are used the lead from one segmentcould be connected to the beginning of a coil of one winding, the nextlead would be connected to the coil of the second winding in the sameslot ata point one-third the number of turns from the beginning, and thenext lead would be connected to the third coil in the slot at a pointtwo-thirds of the turns from the beginning. It will be seen that thisarrangement gives a regular progression of the induced voltages at eachlead, so that the phase of the induced voltages at the several segmentscorresponds to the angular position of the segments. I

My invention will best be referring which Figure 1 showsdiagrammatically a development on a plane surface of an armaturearranged in accordance with my invention, and Figs. 2\and 3 showdiagrammatic views to the accompanying drawings, in

It, however, is sub- 'ject to the following objection: The coils ofunderstood by of the end of the armature-core with coils as ranged andconnected in accordance with my invention. v

In Fig. 1 I have shown a diagram of an armature arranged in accordancewith my invention reduced toits simplest terms in order to avoidunnecessary complication of the drawing. Thus I have shown only twoindependent ,windmgs, oneot these, A, shown in full lines and the other,A, shown in dotted lines. only one coil per slot and only two turns percoil. 1 It will be understood that these speciiic values have beenchosen for the sake of simplicity and that in practice. any number ofindependt-xnt coils of any number of coils per slot and any number o1"lIlI'llS per coil may be employed. 'lhc windings are carried in slots onthe core (J. The winding A is provided with connnutator-leads a, whichare connected at one end in the usual manner to points between adjacentcoils and at the segments is obtained. The phase of the voltage inducedbetween any pair of commutator-leads a is the phase of the voltageinduced in the coil to the opposite ends of which they are connected,while the phase of the induced voltage between any pair of adjacentleads a, is the phase of the resultant of the voltages in two adjacentcoils-that is, it is half-way between the phases of the induced voltagesin the two coils.

On the commutator are placed brushes B Bjwhich are of a width equal toor a little less than the width of a commutator-segment. No brushconsequently can bridge two segments connected to the same winding, andtherefore no short circuits can be produced in commutation. Since thephase of the induced. voltage of each commutatorsegment corresponds tothe angular position of the segment, the difficulty that has heretotoreexisted in machines provided with independent windings does not exist.If the brush is placed inthe best position for commutation with' respectto any one winding, it will also be in the best position for commutationwith respect to the other winding or windings.

In Fig. 2 I have shown diagrammatically three superposed windingscomposed of coils f three turns each in each slot of the core C.

One winding A is shown. in heavy lines, the second wmdmg A in dottedlines, and the lhlHl winding A m light lines. a, a, and

Each winding is shown as having a represent. leads from the respectivewindings to the commutator c, and these leads are connected to differentpoints on the several coils in the manner heretofore explained. In thiscase, since there are three coils, the

connections-to the several coils difier by a, number of turns equal toone-third the total number of turns per coil. Since there are threeseparate windings, the brush B may be oi a width equal to twocommutator-segments without bridging segments connected to the samewinding.

'I he arrangement of Fig. 2 would not be desirable in practice, sincethe several windings would have unequal rcactances because of theirdifferent positions in the slots. One method of arranging the windingsso as to obtain equal reactances is shown in Fig. 3.

In this figure the three windin s instead of being superposed are placedsi e by side in the slots. Aside from this modification the iigure isthe same as Fig. 2 and requires no further description.

It will be understood that I do not wish to limit myself to theparticular arrangement of windings shown in the drawings. For instance,while in Fig. 1 I-have shown what is known as a parallel or lap Windingit is obvious that my invention may be used equally well with whatisknown as a series or wave winding. Furthermore, as has been pointed out,the number of independent windings, the number of coils per slot, andthe number of turns per coil may be varied as desired to meet therequirements of each case.

that I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. In a dynamo-electric machine, a slotted armature-core, a commutatorcarried thereby, a plurality'of independent windings distributed in saidslots, each slot containing coils belonging to a plurality of saidwindings, and leads from said coils to successive commutator-segments,said leads being so connected to said coils that the phase of theinduced voltage at each lead corresponds to the angular position of thecommutatorseg merit to which it is connected.

2. In a dynamo-electric machine, a slotted armature-core, a commutatorcarried thereby, a plurality of independent windings distributed in saidslots, each slot containing I coils belonging to each of' said windings,

leads from said coils to successive commutator-segments, said leadsbeing so connected to said coils that the induced voltages at adjacentleads difi'er in phase by an amount equal to the electrical angulardisplacement of adjacent commutator-segments.

3. In a dynamo-electric machine, a slotted armature-core, a commutatorcarried thereby, a plurality of independent windings distributed in saidslots, each slot containing coils belonging to a plurality of said wind-7 on the colls differing in position by a number of turns bearing thesame ratio to the number of turns in a coil that unity bears to thenumber of independent windings in the slot.

4. In a dynamo-electric machine, a slotted armature-core, a commutatorcarried thereby, N independent windings distributed'in said slots, eachslot containing one or more coils of each winding, and leads from said Icoils to successive commutator-segments, ad-

jacent leads being connected to their respective coils at points on thecoils differing in position by a number of turns bearing to the numberof turns in a coil the ratio 1 N 5. ha dynamo-electric machine, aslotted armature-core, a commutator carried thereby, a plurality ofindependent windings distributed in said slots, each slot containingcoils belonging to a plurality of said windings, leads from said coilst'o successive commutater-segments, said leads being so connected .tosaid coils that the induced voltages at adj acent leads difierinphase byan amount equal to the electrical angular displacement of adj acentcommutator-segments, and brushes bearing on the commutator of a Widthinsufficient to bridge two segments connected to the same winding.

6. In a dynamo-electric machine, a slotted armature-core, a commutatorcarried thereby, N independent windings distributed in said slots, eachslot containing one or more coils of each Winding, leads from said coilsto successive commutator segments, leads being connected to theirrespective coils at points on the coils differing in position by anumber of turns bearing to the number of turns in a coil the ration 3brushes bearing on the commutator of a Width not greater than (N 1)segments.

In witness whereof I have hereunto set my handthis 24th day of August,1905.

MARIUS o. A. LAToUR,

Witnesses:

BENJAMEN B. HULL, HELEN ORFORD adjacent and v

